1. Field of the Invention
The present invention relates to a vehicle-loaded audio device such as a cassette tape player, a CD player or an MD player, and more particularly to a vehicle-loaded audio device suitable for promoting common use of components and achieving a reduction of costs.
2. Description of the Related Art
Generally, a vehicle-loaded audio device comprises a drive mechanism for carrying out recording/playback on and from a medium (e.g., a cassette tape, CD or MD), a front panel provided with an opening for insertion of the medium and a plurality of control keys, a chassis for supporting the drive mechanism and the front panel, a main board attached to the chassis, and so on. Various circuit components, including a microcontroller, are mounted on the main board.
With such a variety of vehicle-loaded audio devices, front panels are different depending on each type of drive mechanism. For example, a front panel having a cassette insertion opening is employed for a cassette tape player, and a front panel having a disk insertion opening is employed for a CD player. Microcontrollers mounted on the main boards are also different depending on each type of drive mechanism. The microcontroller controls the operation of the drive mechanism in accordance with an input signal from any of control keys. disposed on the front panel. For those reasons, in the manufacturing process of several kinds of vehicle-loaded audio devices having different drive mechanisms, it has been customary to prepare respective sets of a front panel, a chassis and a main board which are specific to each type of drive mechanism, and to assemble the sets of components into the vehicle-loaded audio devices.
As an improvement on the above method, U.S. Pat. No. 5,127,057 discloses a manufacturing method for vehicle-loaded audio devices. According to the disclosed method, a sub-board mounting thereon a sub-microcontroller for controlling the operation of a drive mechanism for each of various players is attached to the corresponding drive mechanism, a sub-board mounting thereon a sub-microcontroller for controlling a display, etc. is attached to a front panel for each of the various players, and a main microcontroller for executing various functions common to the various players is mounted on a main board. When manufacturing a particular one of the various players, e.g., a cassette tape player, the drive mechanism for a cassette tape, the front panel for a cassette tape, and the main board are mechanically attached to a main chassis. The sub-board on the drive mechanism side and the sub-board on the front panel side are electrically connected to the main board, following which all the microcontrollers are interconnected by buses.
Such a manufacturing method for vehicle-loaded audio devices has advantages. By preparing the dedicated drive mechanism and the dedicated front panel for each type of player, and attaching the respective sub-boards mounting thereon the dedicated sub-microcontroller to the corresponding drive mechanism and front panel, the other components, i.e., the main board and the main chassis, are common to all the types of player. As compared with the case of preparing the front panel, the main chassis and the main board are dedicated for each drive mechanism, therefore, the total cost including design and development cost and a mold cost can be reduced.
In the related art disclosed in U.S. Pat. No. 5,127,057, however, the main microcontroller mounted on the main board is connected to the sub-microcontrollers on the drive mechanism side and the front panel side by the buses so that various operations of the drive mechanism are executed corresponding to particular keys disposed on the front panel. Accordingly, the main microcontroller on the main board can be common to all the types of player, but the dedicated sub-microcontrollers must be mounted on the drive mechanism and the front panel, respectively. This point has been a substantial obstacle in achieving a cost reduction.
According to the present invention, three components, i.e., one particular drive mechanism, a front panel corresponding to that drive mechanism and a main board, are attached to a main chassis, and at least the drive mechanism is connected to the main board with a connector. A writing unit into which a program for operating the drive mechanism and the other components in an adapted manner can be written, and a circuit unit common to various players are mounted on the main board. With such a construction, when manufacturing a particular product from among those various players, the main board and the main chassis can be used in common to all the types of product. Further, by writing a program into a flash ROM, which constitutes the writing unit, depending on the type of product when it is on a production line, a common microcontroller on the main board can execute the operation of the drive mechanism corresponding to the front panel. It is therefore possible to reduce the total cost including design and development cost and a mold cost to a large extent.
A vehicle-loaded audio device of the present invention comprises one selected from among drive mechanisms for various players, a front panel having an insertion opening for a medium corresponding to the selected one of the drive mechanisms, a main chassis for supporting the front panel and the drive mechanism, and a main board attached to the main chassis, the main board including a connector for connecting the main board and the drive mechanism, a writing unit into which a program for operating the drive mechanism and the other components in an adapted manner can be written, and a circuit unit common to the various players.
The front panel is required to have at least the insertion opening for the medium corresponding to the drive mechanism. In the case of the front panel being provided with at least one control key for operating the drive mechanism, when the front panel is connected to the main board with a connector, a common microcontroller on the main board can execute the operation of the drive mechanism in accordance with input manipulation of the control key.
The drive mechanism may be directly attached to the main chassis. By attaching the drive mechanism to the main chassis through an intermediate bracket, however, flexibility in attachment of each drive mechanism to the main chassis is improved.
Furthermore, a connection terminal of the drive mechanism may be directly connected to the connector on the main board. By connecting the drive mechanism to the main board with the connector through a flexible cable such as a flat cable or a wire, however, flexibility in connection of each drive mechanism to the main board is improved.